My suggestion is to shop around for RTTs and see what the features are across the board. Donut Media did a video comparing a $700(ish) to a $3500 one in their current Hi / Low comparison series. (youtube)
You aren't getting into it cheap, but features add cost. I would also pick a tent before getting a roof rack so you know you are getting one that works, or a tent may have an option to have a built in rack, etc.
Good luck and report back.